Patent GB-199861-A (GB)
Title: Improvements in sewing machines
IPC: D05B73/12
Filed: 1922-04-11
Abstract: 199,861. Sharaf, R. M. April 11, 1922. Insertion-attaching machines; multiple-needle machines; folding devices.-A sewing-machine is provided with means for severing a strip of material from a sheet and bridging the gap so formed by stitching to the severed edges a strip of another material such as lace, braid &c. The machine is provided with means for turning down the raw edges so that they may be turned back by the stitching to form a neat edge, and means are provided for adjusting the feeding and stitchforming mechanism to vary the width of the severed strip. The presser-foot 15 is formed with an extension serving as a guide for the strip to be attached and along which it is moved step by step by laterally-adjustable fingers 22 carried by a feed bar 21 reciprocated by a rocking lever 161, Fig. 17, engaging pins on the bar 21 and on the take-up arm 155 driven by a cam on the main shaft. A pair of folding-plungers 36 sliding in recesses at each side of the presserfoot are actuated at each descent of the needle to turn down at right angles the cut edges of the strip of material. In the arrangement shown in Fig. 2, these plungers are actuated by the engagement of the needle-holding nipple 43 with a rocking lever 41 carried by the presser-foot and connected by rods 45 to rods 47 engaging slots 48 in the plungers. In a modified arrangement the folders 36<a>, Fig. 5, are stationary when in operation but are connected by links 55 to latches 57 pivoted on drop-leaves 59 which may be locked in closed position by bolts 65 or moved by manipulating the latches to lift the folders out of operative position. Trimming or cutting.-Strip-cutting knives 67 are mounted in guides adjacent to the folders and are connected by a pin-and-slot to the latches 57 so that they may be thrown out of gear similarly to the folders. The knives are actuated by bellcrank levers 74 pivoted on the presser engaging lugs 24 on the lace-feed arm 21 so that a cut is made at each up-stroke of the latter while the stitch is being formed. The knives 67 co-operate with fixed blades on the work-plate. In a modi- 'cation shown in Fig. 33, the knives 242 are clamped in blocks 235 carried by an arm 232 pivoted on the presser-bar and are actuated by a rocking lever 244 engaged by a projection on the lace-feed bar. Presser-feet.-Adjustment of the presser-foot to different widths is effected by means of a differential screw arrangement shown in Fig. 13 and comprising a member 78 fixed to the presserbar engaged by a screw 79 turning in the part 15<a> and into which enters a screw 81 of half the pitch secured to the part 15<b>. A pinion 80 is mounted on the end of the screw 79 and is connected by a master gear 82, Figs. 2 and 5, to pinions 80 mounted on sleeves 79<1> engaging screws 81. A scale is provided to facilitate accurate adjustment of the foot-section. Lock stitching by hooks.-Co-operating with the two jogging needles 18, 19 are rotary hooks 102, 103 driven in the same direction bv bevel gearing 108 from a shaft 110 driven by a countershaft 112. These hooks engage the needlethread directly in the outer strokes of the needles, but on the alternate inner strokes thread-catchers 187, 188 first engage, the thread and carry it into the paths of the hooks. These thread-catchers are mounted on pivots 189 and controlled by springs 190 by which they are held in the path of cam-teeth 195 on discs 191 driven by gears 194 from the shaft 112. The cams actuate the catchers on the alternate needle strokes. The hooks 102, 103, their associated thread-catchers and the throat-plates are mounted on adjustable blocks 120, 122 secured by binding screws 123 entering slots in the blocks. The screws may he loosened simultaneously by the manipulation of a hand-wheel which rotates a gear wheel in mesh with pinions on the screws. The adjustment of the blocks is effected by screws 133, 134, Fig. 2 rotated simultaneously by a screw-driver &c. applied to a shaft 140 acting through gearing 138, 136, 135. Feed by dogs.-The feed dogs 113, 114 are independently actuated respectively by concentric rock-shafts 117, 118 connected to feed bars 115, the lift being controlled by arms 119 keyed on a rock-shaft 119<1>. The arms 119 and 115 are slidable on their rock-shafts so that the feed-dogs are adjusted when the blocks 120, 122 are adjusted. To assist the operator in guiding the work by means of a knee-lever or the like connected by suitable mechanism to produce differential movement of the feed dogs, an indicator is provided comprising an indicator arm 261, for tracing the line of the pattern, pivoted at 262, and connected by a link 263 to a pin 265 on a disc 266 geared to a shaft 270 which is connected to the knee-lever &c. Needles vibrating laterally.-The needles 18, 19 are carried in blocks 147, 148 slidable in a thimble 43 secured to a tubular needle-bar 20. Inner extensions 149 of the blocks are formed with slots 150, Fig. 20, in which are engaged pins 166 formed on the rod of an inner rod 163 rotatable within, but reciprocating with, the needle-bar 20. The needles are caused to make their descents in alternate stroke in approximated and separated portions by the rotary oscillation of the rod 163 which is effected by means comprising a pin 170 which enters a straight slot 169 in the bar 20 and on alternate strokes is depressed to pass into a slot in the rod 163 having a portion inclined to the axis. The movement of the pin into the slot is effected by a lever 171 carrying the pin and engaged by a lever 175 the nose 177 of which is caused by a spring 185 to bear on the periphery of a cam 178. The cam is rotated by worm-gearing comprising a gear-wheel 181 and a worm 183 consisting of a single circum. ferential rib of which only the extremity 184 has an axial displacement. The needle-carrying blocks 147, 148 are held steady by friction on those strokes during which the pin 170 is disengaged from the inner slot. Each block is formed in two parts relatively adjustable by screws 199 so that the distance apart of the needles may be adjusted in accordance with the width of the strip. In operation the needles make their descents at one stroke through both pieces of material and at the next through the attached strip only, the cross threads so produced serving to draw up the raw edge of material turned down by the folders 36, as indicated in Fig. 28.